1. Field of the Invention
The present invention relates to a liquid supply nozzle, and more particularly to a liquid supply nozzle stop which automatically stops the liquid supply when a predetermined amount of liquid is supplied.
2. Discussion of the Related Art
A known liquid supply nozzle, which can be used e.g. for supplying fuel from a fuel dispenser in a gas station or the like usually contains, a discharge pipe, a liquid feeding member, and a main valve which is provided between the discharge pipe and the liquid feeding member, an air passage which runs inside the discharge pipe and opens to the atmosphere on the wall of the discharge pipe around the tip thereof, a check valve which generates a negative pressure zone, and a valve open/close mechanism which holds the main valve open when the liquid should be fed and closes the same when a predetermined amount of liquid has been supplied.
The valve open/close mechanism has a diaphragm chamber which is in communication with the air passage normally open to the atmosphere and the negative pressure zone formed around the check valve, and the pressure state of the diaphragm chamber changes depending on whether or not the air passage opening is open. When the above-mentioned opening of the air passage tube on the discharge pipe is blocked by the liquid coming up to the level above the opening, the air passage does not open to the atmosphere, and then the diaphragm chamber is negatively pressurized through another passage from the negative pressure zone. In this way, the main valve, which is kept open by the valve open/close mechanism with a clutch, is closed by release of the clutch when the liquid has been satisfactorily discharged.
A diaphragm is held by being fixed on a rim of a hollow part provided in the nozzle main body, and has a rigid center plate fixed on its center for operating the clutch or the like. Accordingly, a part of the diaphragm where the center plate is fixed will become fatigued because of stress created by the movement of the valve open/close mechanism. The diaphragm in such a condition is easily damaged when a strong external force is applied thereto, for example, by the accidental dropping and subsequent impact of the nozzle on the ground, whereby the valve open/close mechanism does not properly work and the liquid is oversupplied.
In order to solve the above-mentioned drawback, it has been proposed to provide a liquid supply nozzle containing two sets of valve open/close mechanisms therein as disclosed in Japanese Kokai Publication 2 (1990)-172549. The provision of the two valve open/close mechanisms, however, makes the structure of the nozzle complicated and the manufacturing cost is increased.
It is therefore an object of the present invention to provide a liquid supply nozzle with a supplemental function to assist a main automatic liquid supply stoppage function. The liquid supply nozzle comprises: an inlet; a discharge pipe having a free end; a main valve provided between the inlet and the discharge pipe; an air passage provided in the discharge pipe, the air passage having an opening in the discharge pipe adjacent the free end; a negative pressure forming member provided downstream of the main valve and forms a negative pressure zone; a valve open/close mechanism having a diaphragm chamber determined by a diaphragm member and a cap, the diaphragm chamber containing an urging member which presses the diaphragm member, the diaphragm chamber communicating with the air passage and the negative pressure zone, the valve open/close mechanism holding the main valve open, and closing the main valve by movement of the diaphragm member opposing the urging member when a predetermined amount of liquid is supplied; and a liquid supply backup operable when the valve open/close mechanism fails to close the main valve.
Another object of the present invention is to provide the liquid supply nozzle which has a supplemental liquid supply stoppage function when a main automatic liquid supply stoppage function does not appropriately obtained wherein the liquid supply backup of the present invention comprise a compulsory liquid supply suspension mechanism provided in the valve open/close mechanism and adapted to suspend liquid supply when the valve open/close mechanism fails to close the main valve.
A further object of the present invention is to provide the liquid supply nozzle with a relatively simple structure which prevents liquid from being oversupplied even if a diaphragm in the liquid supply nozzle is damaged wherein the compulsory liquid supply suspension mechanism is a press member provided at a space beneath the diaphragm member, the press member adapted to enlarge so as to move the diaphragm member opposing the urging member when the press member absorbs liquid leaked through the diaphragm member Still another object of the present invention is to provide the liquid supply nozzle which positively alarms when the valve open/close mechanism is damaged wherein the liquid supply backup further comprises an alarm unit connected to the press member which visually or sonically alarms leakage of liquid.
Yet another object of the present invention is to provide the above-mentioned liquid supply nozzle which is suitable for feeding or discharging a hydrocarbon-based liquid wherein the diaphragm member is made of an oil resistant material, and the press member is an absorption material which enlarges by absorbing a hydrocarbon-based liquid.
A still further object of the present invention is to provide the above-mentioned liquid supply nozzle in which damage of the diaphragm member can be visually recognized at an early stage, wherein the cap is made of a substantially transparent material permitting visual inspection of the diaphragm member.
A still further object of the present invention is to provide the above-mentioned liquid supply nozzle by which the material of the cap is transparent and suitable for the use wherein the material for the cap is selected from the group consisting of nylon resin and urethane resin.
A still further object of the present invention is to provide the above-mentioned liquid supply nozzle by which the liquid stoppage function can be still attained if a part of the diaphragm member is damaged even without swelling or enlargement of the press member, wherein the diaphragm member is composed of two sheets of rubber.
A still further object of the present invention is to provide the above-mentioned liquid supply nozzle, by which breakage of an upper one of two diaphragms is readily seen from outside of the nozzle through the cap covering the diaphragm member, wherein the two sheets of rubber are in different colors from one another at least on upper surfaces thereof.
A still further object of the present invention is to provide the above-mentioned liquid supply nozzle with a diaphragm member made of a sufficiently oil-resistant material with suitable mechanical properties, wherein the diaphragm member is made of nitrile-butyl rubber.
A still further object of the present invention is to provide the above-mentioned liquid supply nozzle with the liquid supply stoppage function when the diaphragm member is damaged, wherein a press member is in a ring shape and made of a material selected from the group consisting of ethylene-propylene rubber and chloroprene rubber.
A still further object of the present invention is to provide a liquid supply nozzle in which damage of a valve open/close mechanism, especially of the diaphragm member is easily perceived from outside of the nozzle, comprising: an inlet; a discharge pipe having a free end; a main valve provided between the inlet and the discharge pipe; an air passage provided in the discharge pipe, the air passage having an opening in the discharge pipe adjacent the free end; a negative pressure forming member provided downstream of the main valve and forms a negative pressure zone; and a valve open/close mechanism having a diaphragm chamber which is determined by a diaphragm member and a cap, the diaphragm chamber containing an urging member which applies a force to the diaphragm member, the diaphragm chamber communicating with the air passage and the negative pressure zone, the valve open/close mechanism holding the main valve open, and closing the main valve by movement of the diaphragm member opposing the urging member when a predetermined amount of the liquid is supplied, and the diaphragm member is visible through the cap.